/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.common.io;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sss.common.DataReceiver;
import org.sss.mapreduce.Configuration;
import org.sss.mapreduce.GroupID;
import org.sss.mapreduce.SssException;
import org.sss.mapreduce.StorageNode;

/**
 * .
 * NOTE: This class used by only map operation.
 */
public class StreamDBFlatDataReader extends AbstractFlatDataReader{
  @SuppressWarnings("unused")
  private static Logger logger = LoggerFactory.getLogger(StreamDBFlatDataReader.class);

  public StreamDBFlatDataReader(Configuration conf,
                                StorageNode node,
                                GroupID gid,
                                int subhash,
                                DataReceiver<List<byte[]>> next) throws SssException {
    super(conf, node, gid, subhash, next);
  }

  /**
   * .
   */
  @Override
  protected void issueCommands(IOThread iot) throws SssException, IOException {
    StreamDB sdb = iot.getStreamDB(node);
    int count_max = iot.getIOGetBatchCount();
    int limitNBytes = iot.getIOGetLimitNBytes();

    Iterator<byte[]> it = sdb.read(getSource(), subhash, isDestructiveRead()).iterator();
    long nbytes = 0;
    List<byte[]> kvs = new ArrayList<byte[]>(count_max);
    while (it.hasNext()) {
      byte[] key = it.next();
      nbytes += key.length;
      kvs.add(key);
      byte[] value = it.next();
      nbytes += value.length;
      kvs.add(value);
      if (nbytes >= limitNBytes) {
        countup(kvs);
        next.put(kvs);
        nbytes = 0;
        kvs = new ArrayList<byte[]>(count_max);
      }
    }
    if (!kvs.isEmpty()) {
        countup(kvs);
        next.put(kvs);
    }
    next.close();
  }
}
